Mitigating Internal Instrument Coupling for 21 cm Cosmology I: Temporal and Spectral Modeling in Simulations

TL;DR

This paper develops and tests modeling techniques to mitigate internal instrument reflections and antenna coupling in 21 cm cosmology surveys, aiming to improve the detection of the Epoch of Reionization signal.

Contribution

It introduces new methods for modeling and removing systematics in interferometric data without losing the cosmological 21 cm signal.

Findings

Techniques effectively model and remove systematics.

Methods show resistance to 21 cm signal loss.

Application demonstrated on real data from HERA.

Abstract

We study the behavior of internal signal chain reflections and antenna cross coupling as systematics for 21 cm cosmological surveys. We outline the mathematics for how these systematics appear in interferometric visibilities and describe their phenomenology. We then describe techniques for modeling and removing these systematics without attenuating the 21 cm signal in the data. This has critical implications for low-frequency radio surveys aiming to characterize the 21cm signal from the Epoch of Reionization and Cosmic Dawn, as systematics can cause bright foreground emission to contaminate the EoR window and prohibit a robust detection. We also quantify the signal loss properties of the systematic modeling algorithms, and show that our techniques demonstrate resistance against EoR signal loss. In a companion paper, we demonstrate these methods on data from the Hydrogen Epoch of Reionization Array as a proof-of-concept.